Refctor image downloader (#3393)

* Adds configurable setting for maximum remote image size

* Add helper function for downloading image from remote URL

- Will replace existing function
- Performs more thorough sanity checking

* Replace existing image downloading code

- part image uses new generic function
- company image uses new generic function

* Rearrange settings

* Refactor and cleanup existing views / forms

* Add unit testing for image downloader function

* Refactor image downloader forms

- Part image download now uses the API
- Company image download now uses the API
- Remove outdated forms / views / templates

* Increment API version

* Prevent remote image download via API if the setting is not enabled

* Do not attempt to validate or extract image from blank URL

* Fix custom save() serializer methods

InvenTree/common/models.py

@@ -24,7 +24,8 @@ from django.contrib.humanize.templatetags.humanize import naturaltime
 from django.contrib.sites.models import Site
 from django.core.cache import cache
 from django.core.exceptions import AppRegistryNotReady, ValidationError
-from django.core.validators import MinValueValidator, URLValidator
+from django.core.validators import (MaxValueValidator, MinValueValidator,
+                                    URLValidator)
 from django.db import models, transaction
 from django.db.utils import IntegrityError, OperationalError
 from django.urls import reverse
@@ -856,6 +857,18 @@ class InvenTreeSetting(BaseInvenTreeSetting):
             'default': False,
         },
 
+        'INVENTREE_DOWNLOAD_IMAGE_MAX_SIZE': {
+            'name': _('Download Size Limit'),
+            'description': _('Maximum allowable download size for remote image'),
+            'units': 'MB',
+            'default': 1,
+            'validator': [
+                int,
+                MinValueValidator(1),
+                MaxValueValidator(25),
+            ]
+        },
+
         'INVENTREE_REQUIRE_CONFIRM': {
             'name': _('Require confirm'),
             'description': _('Require explicit user confirmation for certain action.'),